Defensive publication

ABSTRACT

SILECERRS OF MUFFLERS FOR INTERNAL COMBUSTION ENGINES ARE DISCLOSED HAVING AT LEAST ONE SURFACE AND PREFERABLY BOTH THE INTERNAL AND EXTERNAL SURFACES, COATED WITH A POLYARLYENE POLYETHER CONTAINING AROMATIC ETHER OR THIOETHER GROUPS IN THE POLYMER CHAIN ORTHO OR PARA TO AT LEAST ONE -SO2- OR -CO- GROUP. THERMOPLASTIC POLYARYLENE POLYETHERS USEFUL HEREIN GENERALLY HAVE AT LEAST SOME UNITS OF THE STRUCTURE:   -PHENYLENE-Y-PHENYLENE-X-   IN WHICH Y IS OXYGEN OR SULFUR OR THE RESIDUE OF AN AROMATIC DIOL SUCH AS 4,4&#39;&#39;-BISPHENOL. THESE POLYMERS ARE RESISTING TO ROAD SALT, SLUSH AND ROAD WATER AND PROTECT THE UNDERLYING METAL SUBSTRATE EVEN AT TEMPERATURES ABOVE 200*C. THE POLYARYLENE POLYETHER COATING IS PREFERABLY APPLIED TO THE SILENNCER OR MUFFLER AFTER THE ARTICLE IS FABRICATED AS WELDING OPERATIONS DESTROY THE INTEGRITY OF THE POLYMER COATING. THE POLYMER IS APPLIED USING CONVENTIONAL DIPPING, SPRAYING, BRUSHING OR POWDER COATING TECHNIQUES AND ARE PREFERABLY CONTAINED IN A SOLVENT SOLUTION. SUITABLE SOLUTIONS FOR COATING POLYARYLENE POLYETHER CONTAIN 5 TO 25 G. BY WEIGHT OF POLYMER IN 100 ML. OF SOLUTION (I.E. 5 TO 15% W./V.) PREFERABLY 10-15% W./V. SUITABLE SOLVENTS INCLUDE ALKYL AND ARYL SULPHONES AND SULPHOXIDES, AMIDES SUCH AS FOR EXPAMPLE DIMETHYLFORMAMIDE, KETONES SUCH AS FOR EXAMPLE CYCLOHEXANE. THE SOLVENT OR MIXTURE OF SOLVENTS USED WILL DEPEND ON VARIOUS FACTORS SUCH AS SOLUTION POT-LIFE REQUIRED, VENTILATION AND SOLVENT EVAPORTION FACILITY AVAILABLE. A PARTICULARLY PREFERRED SOLVENT MIXTURE FOR OPTIMUM SHELF LIFE OF THE COATING SOLUTION CONSISTS OF CYCLOHEXANONE (15 TO 20 PARTS BY VOLUME PREFERABLY ABOUT 18 PARTS ), METHYL ETHYL KETONE (4 TO 7 PARTS PREFERABLY 5 PARTS), METHYL METHYL SULPHOXIDE (1 TO 3 PARTS PREFERABLY 2 PARTS). A PREFERRED CURING PROCEDURE FOR VAPORIZATION OF SOLVENT AFTER COATING REQUIRES HEATING AT 100*C$20*C. FOR 45 TO 90 MINUTES FOLLOWED BY HEATING AT 160*C.$20*C. FOR 90 TO 180 MINUTES.

DEFENSIVE PUBLICA'IIQN UNITED STATES PATENT OFFICE Published at therequest of the applicant or owner in accordance with the Notice of Dec.16, 1969, 869'0.G. 687. The abstracts of Defensive Publicationapplications are identified by distinctly numbered series and arearranged chronologically. The heading of each abstract indicates thenumber of pages of specification, including claims and sheets ofdrawings contained in the application as originally filed. The files ofthese applications are available to the public for inspection andreproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Oflicc makes no assertion as tothe novelty of the disclosed subject matter.

PUBLISHED NOVEMBER 5, 1974 T928,ll06 SILENCERS Victor Jeffrey Leslie,Potters Bar, England, assignor to Imperial Chemical Industries Limited,London, England Filed Dec. 17, 1973, Ser. No. 425,276 Claims priority,application Great Britain, Jan. 26, 1973, 4,125/73 Int. Cl. B44d N36 US.Cl. 11797 No Drawing. 6 Pages Specification Silencers or mufflers forinternal combustion engines are disclosed having at least one surfaceand preferably both the internal and external surfaces, coated with apolyarylene polycther containing aromatic ether or thioether groups inthe polymer chain ortlzo or para to at least one -SO or -CO-- group.Thermoplastic polyarylene polycthers useful herein generally have atleast some units of the structure:

in which y is oxygen or sulfur or the residue of an aromatic diol suchas 4,4'-bisphenol. These polymers are resistant to road salt, slush androad water and protect the underlying metal substrate even attemperatures above 200 C.

The polyarylene polyether coating is preferably applied to the silenceror mufiler after the article is fabricated as welding operations destroythe integrity of the polymer coating. The polymer is applied usingconventional dipping, spraying, brushing or powder coating techniqucsand are preferably contained in a solvent solution.

Suitable solutions for coating polyarylene polyether contain to 25 g. byweight of polymer in 100 ml. of solution (i.e. 5 to 25% w./v.)preferably 1015% w./v. Suitable solvents include alkyl and arylsulphones and sulphoxides, amides such as for exampledirncthylformamide, ketones such as for example cyclohexanone. Thesolvent or mixture of solvents used will depend on various factors suchas solution pot-life required, ventilation and solvent evaporationfacility available. A particularly preferred solvent mixture for optimumshelf life of the coating solution consists of cyclohexanone to parts byvolume preferably about 18 parts), methyl ethyl ketone (4 to 7 partspreferably 5 parts) and dimethyl sulphoxide (1 to 3 parts preferably 2parts). A preferred curing procedure for vaporization of solvent aftercoating requires heating at 100 C.:20 C. for to minutes followed byheating at C.- '-20 C. for 90 to minutes.

